Janice pays the young boy with a two-dollar note. The US Treasury had ceased issuing those bills in 1966, but it was relaunched in 1976 to mark the Bicentennial. This episode aired in November of that year.
McGarrett expresses surprise that anyone would break into Five-O's new headquarters and leave without stealing anything, yet the very same scenario occurred at their previous location in Welcome to Our Branch Office (1974).